Recommendation ITU-T G.8275 specifies common aspects of phase and time profiles defined in ITU‑T G.8275.1 and ITU-T G.8275.2. This Recommendation includes the precision time protocol (PTP) functions per IEEE 1588 that are necessary to ensure interoperability for the delivery of accurate phase/time synchronization. This amendment provides the following updates: Updates Appendix III. Splits the contents of clause G.1 into three sub-clauses. Merges two tables of Appendix XII into one table. Adds editorial enhancements throughout the document.